Mechanism arrangement for orthopedic simulator

• US 20070169561A1
• Filed: 01/05/2007
• Published: 07/26/2007
• Est. Priority Date: 01/13/2006
• Status: Active Grant

• Current Assignee: MTS Systems Corporation (Illinois Tool Works Inc.)
• Original Assignee: MTS Systems Corporation (Illinois Tool Works Inc.)
• Inventors: Schulz, Bradley D., Fahrendorff, Harold F., Willis, Dennis J., Leska, Paul J.
• Granted Patent: US 8,156,824 B2
• Time in Patent Office: Days
• US Class Current: 73/794
• CPC Class Codes: A61F 2/442 Intervertebral or spinal discs, e.g. resilient non-disc-shaped intervertebral inflatable pockets A61F2/441; non-disc-shaped intervertebral fusion implants A61F2/4455
• CPC Class Codes: A61F 2/4425 made of articulated components
• CPC Class Codes: A61F 2/468 Testing instruments for artificial joints for testing non-implantable prostheses A61F2/76
• CPC Class Codes: A61F 2002/7695 Means for testing non-implantable prostheses for testing implantable prostheses A61F2240/008; for implanting artificial joints A61F2/468
• CPC Class Codes: G01N 2203/0016 Tensile or compressive
• CPC Class Codes: G01N 2203/0017 Tensile
• CPC Class Codes: G01N 2203/0019 Compressive
• CPC Class Codes: G01N 2203/0021 Torsional
• CPC Class Codes: G01N 2203/0023 Bending
• CPC Class Codes: G01N 2203/0026 Combination of several types of applied forces
• CPC Class Codes: G01N 2203/0089 Biorheological properties
• CPC Class Codes: G01N 2203/0242 With circulation of a fluid
• CPC Class Codes: G01N 2203/0246 Special simulation of "in situ" conditions, scale models or dummies
• CPC Class Codes: G01N 2203/0256 Triaxial, i.e. the forces being applied along three normal axes of the specimen
• CPC Class Codes: G01N 2203/0476 in parallel
• CPC Class Codes: G01N 3/00 Investigating strength properties of solid materials by application of mechanical stress
• CPC Class Codes: G01N 3/32 by applying repeated or pulsating forces

Abstract

An orthopedic simulator is provided with a mechanism with a plurality of sub-mechanisms that generate relative motions between the portions of orthopedic devices, such as spinal disc implants. The sub-mechanisms are configured to be nested so as to place the sub-mechanism with the highest required performance closest to the specimen.

Claims

1. An orthopedic simulator with a mechanism for applying motions and forces to a test specimen, comprising:

a plurality of sub-mechanisms of the mechanism, the sub-mechanisms respectively applying to the test specimen motions and forces with respect to different axes, with at least one of the motions or forces being the motion or force requiring a most demanding performance of the motions or forces applied to the test specimen;

wherein the sub-mechanism that applies the motion or force requiring the most demanding performance is sequentially closest to the test specimen in comparison to the other sub-mechanisms.

2. The simulator of claim 1, wherein the sub-mechanisms are nested such that the sub-mechanisms requiring more demanding performance are sequentially closer to the test specimen than the sub-mechanisms requiring less demanding performance.

3. The simulator of claim 2, further comprising drives coupled to the sub-mechanisms to drive the sub-mechanisms, wherein each drive is sequentially further from the test specimen than the sub-mechanism being driven by that drive.

4. The simulator of claim 2, wherein the motions include an My motion, an Mx motion and an Mz motion, and the forces include an Fx force, an Fy force and a Fz force.

5. The simulator of claim 4, wherein the My motion requires the most demanding performance of the motions and the Fy force requires the most demanding performance of the forces, such that the sub-mechanism for applying the My motion and the sub-mechanism for applying the Fy force are sequentially closer to the test specimen than the other sub-mechanisms.

6. The simulator of claim 5, wherein the test specimen is a spinal implant with a superior portion and an inferior portion and the My motion represents flexion/extension, the Mx motion represents lateral bending and the Mz motion represents axial rotation.

7. The simulator of claim 6, wherein the sub-mechanism for applying the My motion is the sequentially closest sub-mechanism to the superior portion of the test specimen and the sub-mechanism for applying the Fy force is the sequentially closest sub-mechanism to the inferior portion of the specimen.

8. The simulator of claim 7, wherein the sub-mechanism for applying the Mx motion is the next sequentially closest sub-mechanism to the superior portion of the test specimen.

9. The simulator of claim 8, wherein the sub-mechanisms for applying the Fx force, for applying the Fz force and for applying the Fz motion are the next sequentially closest sub-mechanisms to the inferior portion of the test specimen in the order of Fx, Fz and Mz, from closer to further.

10. An orthopedic simulator comprising:

an My sub-mechanism configured to apply an My motion to a first portion of a test specimen; and

an Mx sub-mechanism configured to apply and Mx motion to the first portion of the test specimen;

the Mx sub-mechanism being sequentially further from the first portion of the test specimen than the My sub-mechanism.

11. The simulator of claim 10, further comprising a plurality of test stations at which respective test specimens are tested, the My and Mx sub-mechanisms respectively applying the My and Mx motions simultaneously to the test specimens.

12. The simulator of claim 11, wherein the My sub-mechanism includes gimbals respectively coupled to the test specimens to apply the My motion to the test specimen, and wherein each of the gimbals is directly connected to a first common solid cross-piece such that the gimbals are each directly driven via the common cross-piece.

13. The simulator of claim 12, further comprising an Fx and Fy force sub-mechanism, an Fz force sub-mechanism and an Mz sub-mechanism, the Fx and Fy force sub-mechanism being sequentially closer to a second portion of the test specimen than the Fz force sub-mechanism and the Mz sub-mechanism.

14. The simulator of claim 13, wherein the Mz sub-mechanism includes independent linkages to apply Mz motion to each of the test specimens, the independent linkages each being directly connected to a solid second common cross-piece such that each of the independent linkages is directly driven via the second common cross-piece.

15. The simulator of claim 14, wherein the Fz force sub-mechanism comprises a low-friction vertical load actuator.

16. The simulator of claim 13, wherein the test specimens are spinal implants with a superior portion and an inferior portion and the My motion represents flexion/extension, the Mx motion represents lateral bending and the Mz motion represents axial rotation.

17. A spinal implant test machine, comprising:

a flexion/extension sub-mechanism for applying flexion/extension rotational motion to a test specimen of a spinal implant;

a lateral bending sub-mechanism for applying lateral bending rotation motion to the test specimen; and

an axial rotation sub-mechanism for applying axial rotational motion to the test specimen;

wherein an Euler sequence of rotational motion applied to the test specimen is flexion/extension>

lateral bending>

axial rotation.

18. The test machine of claim 17, wherein the flexion/extension sub-mechanism, the lateral bending sub-mechanism and the axial rotation sub-mechanism are independent from one another.

19. The test machine of claim 17, further comprising a controller coupled to the flexion/extension sub-mechanism, the lateral bending sub-mechanism and the axial rotation sub-mechanism, the controller configured to control the movements of the sub-mechanisms and the phases between the sub-mechanisms.